Cathode ray deflection apparatus



April 11, 1939. H. o. ROOSENSTEIN ET AL 2,153,643

CATHODE RAY DEFLECTION A'PPARATUS Filed Feb.

B mmL Y CLE mm m N R E 0 Vnv mn n 0% A M M Y Patented Apr. 11, 1939 UNITED STATES PATENT OFFICE CATHODE RAY DEFLECTION APPARATUS Hans Otto Roosenstein and Horst Hewel, Berlin,

Application February 12, 1937, Serial No. 125,382 In Germany January 24, 1936 4 Claims.

Our invention relates to iron core magnetic coils, and more particularly to such a coil for use with cathode rays for deflection purposes.

Heretofore iron core coils had been used for the magnetic deflection apparatus for cathode rays particularly as adapted to use for television purposes or for oscillographic purposes with socalled Braun tubes. These devices heretofore used have in general comprised two coil halves which are disposed on two branches or legs consisting of magnetic material between which is contained the air gap wherein is placed the tube itself, and one or two yokes have been provided such that the magnetic flux closes through an iron path. Arrangements of this type have the disadvantage however that the flux in the air gap of the iron core is rendered sufliciently homogeneous for use only when the iron for the pole pieces has been of comparatively large dimensions. It is, therefore, one of the objects of my invention to provide an iron core magnetic coil in which this disadvantage is obviated.

In general, this invention consists of the provision of one or two main yokes and one or two secondary yokes and, where desirable an air gap is provided in one or both of the secondary yokes. This arrangement allows the provision of a device in which the magnetic flux branched off by the supplementary yokes from the main flux has a course of equal sense and at a line approximately parallel with the line connecting the main pole pieces and the intersecting axis of the tube.

Two embodiments of the invention are illustrated in the drawing, in which Fig. 1 represents one embodiment of my invention,

Fig. 2 is a cross-sectional view along the line CD of Fig. 1,

Fig. 3 is another embodiment of my invention,

and

Fig. 4 is a cross-sectional view along the line CD of Fig. 3.

Referring to Fig. 1, there are provided two coil parts I0 and II wound about two legs I2 and I3 respectively, joined to which are two main yokes I4 and I5. On the two legs I2 and I3 are mounted two pole pieces I6 and I1, and the distribution of the lines of force about these pole pieces is clearly shown in the drawing on the right side of center line AB. In accordance with this invention, two secondary yokes are pro vided comprising the sections I8 to 2|. The ends of the two secondary yokes are slotted as shown at 22, and they may be fixed in the correct position with respect to the rest of the yoke members by screws 23. The fiux closing through yoke I8 and I 9, in which is contained an air gay, is shown clearly on the drawing with the result that the field intensity which is usually small at greater distances from center line AB of the flux closing over main yokes I4, I5 is compensated.

The cross-sectional arrangement along the line CD is clearly illustrated in Fig. 2 in which the reference characters indicate the same parts as 10 in Fig. 1.

Referring to Fig. 3, there is shown an embodiment in which only one main yoke I4 is provided, and one sectional yoke 20 and 2| made up in the same fashion as the secondary yokes in Fig. 1 is provided. To the right of center line AB, the non-homogeneity of the flux closing through the legs I2 and I3 and yoke I4 is eliminated by the flux in the air gap of the secondary yoke 20 and ZI in the same manner as explained with reference to Fig. 1. To the left of the center line AB, the stray flux of winding 24 effects in a similar manner at elimination of the nonhomogeneity of the deflecting field.

It will be realized, of course, that we may, instead of using air gaps in the secondary yokes, merely constrict the cross-section of the iron and thus perform a similar compensation.

What is claimed is:

1. In combination, a cathode ray tube having means for developing an electron beam, and an apparatus for deflecting said electron beam comprising a main yoke member, a pair of pole pieces which when energized provide an uneven field intensity value along the line of deflection of said electron beam joined to said main yoke member, a supplementary yoke member having an air gap therein joined to said main yoke member, and means for energizing said main yoke member, said supplementary yoke member and said pole pieces, said latter means and said supplementary yoke member each being positioned at a finite distance from said pole pieces whereby the field from said supplementary yoke member and said energizing means substantially compensates for inequalities in field intensity along the line of deflection of said beam.

2. In combination, a cathode ray tube having means for developing an electron beam, and an apparatus for deflecting said electron beam comprising a main yoke member, a plurality of pole members which when energized provides an uneven field intensity along the line of deflection of said electron beam joined to said main yoke member, a pair of adjustable supplementary yoke members each having an air gap therein and spaced apart from said pole members a finite distance whereby the flux established by said supplementary yoke members when energized substantially compensates for the inequalities in field intensity along the line of deflection of said beam, and means for energizing said pole members and yoke members.

3. In combination, a cathode ray tube having means for developing an electron beam, and an apparatus for deflecting said electron beam comprising a main yoke member, a plurality of pole members which when energized provides an uneven field intensity along the line of deflection of said electron beam joined to said main yoke member, a pair of adjustable supplementary yoke members each having a constricted section therein and spaced apart from said pole members a finite distance whereby the fiux established by said supplementary yoke members when energized substantially compensates for the inequalities in field intensity along the line of deflection of said beam, and means for energizing said pole members and yoke members.

4. In combination, a cathode ray tube having means for developing an electron beam, and an apparatus for deflecting said electron beam comprising a main yoke member, a pair of pole pieces which when energized provide an uneven field intensity value along the line of deflection of said electron beam joined to said main yoke member, an adjustable supplementary yoke member having an air gap therein joined to said main yoke member, and means for energizing said main yoke member, said supplementary yoke member and said pole pieces, said latter means and said supplementary yoke member each being positioned at a finite distance from said pole pieces whereby the field from said supplementary yoke member and said energizing means substantially compensates for inequalities in field intensity along the line of deflection of said beam.

HANS OTTO ROOSENSTEIN. HORST HEWEL. 

